Risk of Ehrlichia species exposure on the rise across portions of U.S.

IDEXX Laboratories recently reported that dogs in the south central and eastern regions of the country are being exposed to a greater number of ticks and tick-borne diseases than once thought, according to a company-issued press release. Researchers with IDEXX compared reference laboratory results conducted in 2011 with current results from one of its SNAP diagnostic tests—also run at the reference laboratory—and found that there was up to a fourfold increase in Ehrlichia species exposure this year.

But is this the result of improved laboratory tests and better detection, or is the nation’s tick population growing and branching out into uncharted territory? It’s true that the company’s SNAP 4Dx Plus test, which screens for a number of common tick-borne pathogens, was recently upgraded to include antibody detection for Ehrlichia ewingii, but that’s only part of the story, says Susan Little, DVM, PhD, DEVPC (right), professor of veterinary parasitology at Oklahoma State University. “That test has wider platform and is detecting an agent that we didn’t previously have serologic assays to detect,” she says. “But the vector tick that transmits Ehrlichia ewingii, the most common Ehrlichia species infecting dogs in the U.S., now has a broader geographic distribution, too.”

Ehrlichia ewingii is transmitted by the lone star tick, and dogs in the southern part of the U.S. have always been at risk for this type of Ehrlichiosis, due to the tick’s overwhelming presence in that region. But even that indigenous tick population is growing, says Little, and now the lone star tick is migrating north into much of the eastern two-thirds of the country.

However, Little is encouraged by the fact that laboratories such as IDEXX are striving to create better diagnostic tests that pick up more disease-causing agents, like Ehrlichia ewingii. “We need to characterize the full gamut of what’s out there and have diagnostic tests that identify the infection,” she says. “Many veterinarians recognize that a patient has a tick-borne disease, but they’re not able to figure out what it is.”

But that could be changing, as evidenced by the recent upgrade in the IDEXX test. “While many veterinarians in highly endemic areas are familiar with acute E. ewingii infections, we don’t know a lot about this pathogen because testing for it has been limited until now,” says Melissa Beall, DVM, PhD, manager of medical affairs at IDEXX. “IDEXX is excited to be able to help veterinarians screen for a pathogen and evidence of a tick species that is fast becoming a larger threat to people and pets in more parts of the country.”

In order to keep that threat to a minimum, Little suggests that veterinarians follow the Companion Animal Parasite Council’s recommendations and urge clients to practice year-round tick control and prevention. “We need to be more adamant with clients about year-round tick control for dogs and cats,” Little says. “Tick control protects dogs and cats from tick-borne diseases—the ones we know about and the ones we’re still finding out about.”

For more information about tick control and prevention, visit capcvet.org.